Is mercury in composite resin filling?

No. Composites are often the first choice as an alternative to the silver mercury fillings.
No. Composite fillings are made up of a variety of materials, but mercury is not one of them. Composite fillings are mercury-free!
No. I agree with dr. Quon, mercury is only found in amalgam fillings or restorations. White colored fillings are either made out of resin composites or porcelain. White colored fillings and porcelain restorations are more technique sensitive and require more care and precision to do them well and to make them look attractive and last a long time.